Turek et al. [21] and Rudic et al [22] employing gene knockout mice demonstrate that the disruption of the core molecular clock machinery including Bmal1 and CLOCK leads to hyperphagia and obesity, and metabolic syndrome characterized by hyperleptinemia, hyperlipidemia, hepatic steatosis, and hyperglycemia [21], [22]. Here, CLOCK is linked to obesity due to melanocortin 4 receptor deficiency.